1. Technical Field
The present invention relates generally to mobile communication systems and more particularly, to general packet radio services for delivering data over a circuit switched telephone network.
2. Related Art
The general packet radio service (GPRS) is a new non-voice value added service that allows information to be sent and received across a mobile telephone network. It supplements, or rides on top, of today""s circuit switched data and short message service networks. The theoretical maximum speed of GPRS includes speeds of up to 171.2 kilobits per second (kbps). This maximum speed is achievable in GPRS systems using all eight timeslots at the same time in a time division multiple access (TDMA) context.
This speed is about three times as fast as data transmission speeds possible over today""s fixed telecommunication networks and ten times as fast as current circuit switched data services on Global System for Mobile Communications (GSM) standard TDMA networks. Thus, GPRS systems are advantageous in that they require less system resources to transmit a fixed amount of data in comparison to using a traditional circuit switched approach. By allowing information to be transmitted more quickly, immediately, and efficiently, across the mobile network, GPRS may well be a relatively less costly mobile data service compared to SMS and circuit switched data services.
GPRS also facilitates instant connections in which information can be sent or received immediately as the need arises, subject to radio coverage. No dial up modem connection is necessary. GPRS, similar to some broadband connections for personal computers, often is referred to as being xe2x80x9calways connected.xe2x80x9d Thus, another one of the advantages of GPRS is that data may be transmitted immediately, whenever the need arises. In contrast to circuit switched data networks in which a connection must be established to transmit a data packet or data file, GPRS operation is extremely efficient in those situations in which a small amount of data is to be sent.
As the emphasis of many designs today are to create wireless computer networks, and to connect data devices including personal computers to wireless transceivers and mobile terminals, such a system that provides instantaneous response is very important for time critical applications, and, more generally, for the implementation of wireless computer networks.
For example, a remote credit card authorization system implemented in a wireless network can be greatly improved if it is unnecessary for the customer to wait the amount of time that is required to establish a connection. Anyone that has waited at a cash register for credit authorization while a modem dials in and transmits account information can readily appreciate this advantage.
Additionally, GPRS facilitates the use of Internet applications not only from personal computers, but also from appliances and machines. It is anticipated that appliances will be designed to be coupled to the Internet to facilitate control either onsite or remotely. While some people envision connecting these appliances to a network port by physical lines, it would clearly be advantageous to be able to connect such appliances to the Internet through a wireless link. GPRS will facilitate the creation of Internet controlled appliance networks through a wireless medium.
As suggested before, GPRS involves overlaying a packet based air interface on an existing circuit switched wireless network. For example, the circuit switched wireless network may comprise a GSM network. Accordingly, the user is given an option to utilize a packet based data service. In order to overlay a packet based air interface over a circuit switched network, the GPRS standard defines new infrastructure nodes to minimize the impact to existing networks in terms of hardware and software.
One advantage of GPRS is that the packet switching that results from the infrastructure nodes allows the use of GPRS radio resources only when users actually are sending or receiving data. Unlike traditional circuit switched voice networks, a connection is not continuously reserved for a user for the intermittent transmission of data. This efficient use of scarce radio resources means that larger number of GPRS users can share the same bandwidth and be served from a single base station or cell. The actual number of users, of course, that may use the system at one time depends on the amount of data being transferred.
As mentioned above, GPRS can obtain transmission data speeds of 171.2 kbps. To obtain such a speed, however, a user would have to transmit data packets over all eight timeslots without any air protection. In reality, network operators probably will rarely allow all timeslots to be used by a single GPRS user. Additionally, GPRS terminals are expected to be limited to using just a subset of the available timeslots in a TDMA network. The bandwidth available to GPRS, therefore, is limited. Because this bandwidth is limited, it is anticipated that throughput capacity issues will occasionally be experienced.
There is, therefore, a need realized by the present inventors to implement a quality of service rating scheme to assist the network provider in assigning priority among the various users competing for the scarce radio resources. One problem, however, is that the present GPRS over the air interfaces do not contain provisioning for quality of service ratings. Accordingly, while there is a need to establish a quality of service implementation, doing so is difficult without creating an interface change. One problem with creating an interface change to support QoS provisioning, however, is that it would require interface changes including software and perhaps hardware changes to all existing GPRS equipment. Thus, it would be desirable, if possible, to implement a QoS system that does not require software or hardware changes in existing equipment to render that equipment compatible with a change to the over-the-air interface. What is needed, therefore, is a method and apparatus that supports QoS provisioning without changing the interface so that there will be no impact on existing GPRS equipment.
An inventive method and apparatus support quality of service provisioning for a given mobile terminal without requiring changes to established interfaces for the general packet radio service network. More specifically, a temporary logical link identifier (TLLI) is assigned in a manner that implicitly reflects a QoS rating for a mobile terminal. In one embodiment of the present invention, a serving GPRS support node (SGSN) assigns a TLLI within a first range for a first QoS rating and within a second range for a second QoS rating. Alternatively, the SGSN assigns a TLLI having an even numerical value for a first QoS rating and an odd numerical value for a second QoS rating.
In an alternative embodiment of the invention, the TLLI assignments are arranged in a plurality of ranges, wherein each of the plurality of ranges reflects a corresponding QoS rating. Accordingly, differentiated QoS can be provided between the SGSN and a base station subsystem by associating the quality of service with a value range for the TLLI.
In operation of one embodiment of the present invention, whenever a mobile terminal attaches to the GPRS network, a subscriber profile is downloaded from a home location register (HLR) by the SGSN. The subscriber profile contains information indicating the quality of service allowed for the mobile terminal. Based upon the profile information, the SGSN assigns a TLLI in the appropriate characteristic. The characteristic may be an even or odd value of the TLLI, a value that is within a numerical range or a value determined by a formulaic calculation. The SGSN can control the priority of data transmissions being sent to each mobile terminal by using the assigned TLLI to imply a corresponding QoS rating for the mobile terminal. Alternatively, the SGSN determines a QoS rating based upon call parameters such as call type. Accordingly, the SGSN generates and transmits a TLLI number to the base station for delivery to the mobile station based upon the determined QoS rating.
The base transceiver system (BTS) that receives the TLLI reflecting a QoS rating may utilize the TLLI in a plurality of ways. First, the BTS may use the TLLI value in deciding what air link resources to allocate to the mobile terminal. Secondly, the BTS may use the TLLI for prioritizing transmissions of a mobile terminal originated data on the backhaul in the base station subsystem.
This solution may be implemented within the current standards, with no changes to the interface with the mobile terminal, as long as the scheme is supported by the SGSN and the BSS. This invention is applicable to GPRS products for both GSM and North American TDMA systems as well as all other time division multiple access systems.